1. Field
The present invention generally relates to a power supply circuit, an image forming apparatus, and a method for supplying a power to the image forming apparatus, and more particularly, to a power supply circuit that outputs a direct current voltage and a pseudo-alternating current voltage.
2. Description
At present, with the increased digitalization of information, image processing devices such as printers used for outputting computerized information, facsimiles, scanners used for computerizing documents, have become essentials. These image processing devices are often constituted as multi-function peripherals (MFP) and used as printers, facsimiles, scanners, and copiers equipped with image scanning, image forming, and communication capabilities.
The image forming apparatuses used for outputting computerized documents charge a photoreceptor and then later clean the photoreceptor using alternating current (AC). However, AC transformers are expensive and large. Therefore, in order to reduce the cost and make the apparatus compact, typically a transformer is used that is compact and inexpensive and outputs alternating direct-current (DC) waveforms of different values to replicate a pseudo-AC waveform.
Alternatively, in order to further reduce the cost, a single transformer is used to produce a multi-purpose pseudo-AC waveform, in which the pseudo-AC waveform is used as is for one purpose or rectified and used as the DC waveform for another purpose.
One technique to generate a stable AC waveform, for example, involves clamping the AC voltage, input to an amplified circuit, at a constant voltage, so that the amplitude of the voltage after being raised can be stabilized by a relatively simple configuration.
In above-described method to rectify the pseudo-AC waveform to the DC waveforms, only one DC voltage that is half the total amplitude of the pseudo-AC waveform can be generated. For example, even when substantially the same voltage is required for the amplitude of the pseudo-AC waveform and for the DC voltage, the desired DC voltage cannot be generated from the desired amplitude of the pseudo-AC waveform.